You can read the (dry) abstract here. But in retrospect, I think the puzzle is better described by the first 1.5 paragraghs of the chapter:

Large corporate law firms are in the business of selling legal expertise to clients, usually by the hour and preferably at a premium price. Without high quality lawyers, these organizations have nothing to sell. Therefore, it stands to reason that law firms operating in a highly competitive market would seek to answer the most fundamental questions at the heart of their business: Who succeeds at our firm? Why do they succeed? What traits do they share in common? Can we recruit and develop more of these individuals? What are the characteristics of lawyers who prioritize building the organization rather than maximizing their personal income? Unless a firm has a realistic grasp of these human capital issues — which go to the very heart its business — it cannot make intelligent trade-offs. Such a firm thus becomes susceptible to paying too much for the wrong input, or ignoring the right input available at a bargain price.

In my study of this market over the last several years, I have observed a remarkable indifference to these questions. ...